Aluminum trailing arm weight

[Plavan]

Hi Guys-
I just wanted to forward a picture of a clean and bare aluminum trailing arm. 10.48 Pounds. The E-brake area was cut out since this is going on my race car to reduce a little more weight. Plus the shock mount was shaved a bit. Once I get a steel one out (and bare), I will weigh that. I know they have been compared before, I just want to see if it is accurate

These damn Porsche's are making me broke. You all know the feeling.... Hmmmm the motor is out being rebuilt, I should change the trailing arms to monoballs.... Well, the arms are going to be off so I might as well upgrade to Aluminum trailing arms.... Well in that case I should get new shocks all the way around and have them revalved.... I guess since I am doing the shocks, I should find some Bilstein Struts and have the spindle raised... Since I am messing with the front A -arms, I should go with PolyBronze bushings because I have monoballs on the rear now..... A NEVER ENDING SAGA!!!
HELP ME!

[Jim Richards]

Chad, just send me your car and I'll take over for you.

BTW, beautiful trailing arm.

[304065]

Chad,

Thanks for posting this. That's consistent with Calzia's findings, but he weighed the arm with the bearing installed and got 12#. How much did the ear for the parking brake weigh? What are the dimensions of the shock mount now that you machined it?

I know what you mean about the classic "improvement syndrome."

I have almost all the parts I need for this conversion. . . but the list gets pretty long. . . drop engine. . .redo oil tank while engine out. . . monoballs, Al arms, new bearings, new bearing retainers, new nut, new cotter pin, WEVO springplates (as soon as they are in production). . .new SS brake lines. . . new steel hardlines. . . bigger torsion bars. . .revalve Bilsteins to match bigger bars. . .

and then you start on the FRONT!

Of course, all that headache goes away when the first green drops.

[v9ff]

What years had the alunimum trailing arm?

[304065]

74-

[Plavan]

John-
The parking brake "ear" is very minimal. Probably and ounce or two. They milled about an inch off the shock mount to fit my 69.

[Britain Smith]

Can you elaborate on what needs to be milled off to fit a '69? I have a set of aluminum arms that will be going on my '69 and I wasn't aware that I needed to modify the arms any.

-Britain

[304065]

Britain,

Do a search here, Sherwood actually wrote the article in EXCELLENCE that describes the procedure. The issue is that the later arms use a 14mm lower shock mount, which may require bashing in the heat exchanger, removing the shock's dust shield, or machining some aluminum off the control arm (there's a steel insert in the arm) to make it fit without interference.

[Plavan]

Here is the verdict. Steel arm 15.12 pounds. Aluminum 10.48 pounds. These are bare arms without the bearings installed.
Cool stuff.

[randywebb]

Thanks for posting that.

Dig your shoes BTW.

[Elombard]

WOW 5 lbs per wheel is HUGE! It seems like you could actually feel the difference in a street car, let alone a race car. Would this not make for a considerably smoother ride because of the faster response time of the rear wheels.

Also, what % does that shift your weight bias forward? ~ 1/2%? That seems significant too. I imagine it will change your corner balance adjustments on a race car and possibly shock and sway bar settings as well.

[arrivederci]

Very very clean chad. Any tips before I get started cleaning the set that's going on my '72?

I already spent half a day cleaning the spring plates with mineral spirits, etc. There's got to be an easier way!

[Plavan]

I can't take credit for the cleaning. Allan at Aase did the cleaning and weighing. He wanted to see what the difference was for himself also. I know he just media blasts them. Media blasting is the key with any cleaning. It is so easy and fast if you have a place you can do it.
I will be throwing the aluminum arms on with the monoballs today. It's always more fun working with clean parts